Chinese ace Ding Junhui was edged out of the World Snooker Championship
Ding, 37, trailed 5-4 after Tuesday's first session and then dragged the match into the deciding frame by winning two frames in a row on Wednesday.
But world No. 17 Lisowski kept his composure in the last frame, firing in two sensational long range reds to seal the victory.
Ding, suffering his fourth consecutive first-round defeat at the World Championship, became the seventh seeded player to lose in the opening round this year.
Si Jiahui became the only Chinese player that reached the last 16 as the 21-year-old ousted three-time world champion Mark Williams 10-9 on Tuesday.
Si will next face qualifier Jak Jones, who outplayed China's 11th seed Zhang Anda 10-4.